Behavioral interventions for vaccination uptake: A systematic review and meta-analysis

Background Human behavior and more specifically behavioral insight-based approaches to vaccine uptake have often been overlooked. While there have been a few narrative reviews indexed in Medline on behavioral interventions to increase vaccine uptake, to our knowledge, none have been systematic reviews and meta-analyses covering not just high but also low-and-middle income countries. Methods We included 613 studies from the Medline database in our systematic review and meta-analysis categorizing different behavioral interventions in to 9 domains: education campaigns, on-site vaccination, incentives, free vaccination, institutional recommendation, provider recommendation, reminder and recall, message framing, and vaccine champion. Additionally, considering that there is variability in the acceptance of vaccines among different populations, we assessed studies from both high-income countries (HIC) and low- to middle-income countries (LMIC), separately. Findings Our results show that behavioral interventions can considerably improve vaccine uptake in most settings. All domains that we examined improved vaccine uptake with the highest effect size associated with Provider Recommendation (OR: 3.4 (95%CI: 2.5-4.6); Domain: motivation) and Onsite vaccination (OR: 2.9 (95%CI: 2.3-3.7); Domain: practical issues). Although the number of studies from LMIC was smaller, the quality of studies was similar across HIC and LMIC. However, effect sizes were different. Interpretation Our findings indicate that “provider recommendation” and “on-site vaccination” along with other behavioral interventions can be employed to increase vaccination rates globally.


APPENDIX C
The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach GRADE approach assesses the quality of evidence and strength of recommendation in healthcare settings and is widely used during systematic review and clinical guidelines development processes.The approach has 2 components: 1) Quality of evidence Quality of evidence is rated as follows: Grade Description High There is a lot of confidence that the true effect lies close to that of the estimated effect.

Moderate
There is moderate confidence in the estimated effect: The true effect is likely to be close to the estimated effect, but there is a possibility that it is substantially different.

Low
There is limited effect in the estimated effect: The true effect might be substantially different from the estimated effect.

Very Low
There is very little confidence in the estimated effect: The true effect is likely to be substantially different from the estimated effect.GRADE judgments refer not to individual studies but to a body of evidence.The quality of evidence for each patient important outcome is assessed based on study design and strengths and limitations present across the body of evidence.Randomized trials provide, in general, stronger evidence than observational studies.Rigorous observational studies provide stronger evidence than uncontrolled case series.In the GRADE approach, randomized trials without important limitations constitute high quality evidence.Observational studies without special strengths or important limitations constitute low quality evidence.Limitations to consider: a) Risk of bias (study limitations) including lack of allocation concealment; lack of blinding, particularly if outcomes are subjective and their assessment highly susceptible to bias; a large loss to follow-up; failure to adhere to an intention to treat analysis; stopping early for benefit; or selective reporting of outcomes b) Inconsistent results across studies c) Indirectness of evidence d) Imprecision of estimate e) Publication bias Strengths to consider: a) Size of the effect estimate.Larger the magnitude of effect, stronger the evidence b) Identification of bias working against the treatment effect c) Presence of dose-response gradient GRADE starts with the study design to rate the quality of evidence and then rates it downwards or upwards depending on the limitations and strengths as shown in the table below: 2) Strength of recommendation GRADE rates strength of recommendation either as strong or weak.Strong recommendation is made when desirable effects certainly outweigh undesirable effects (or vice versa) while a weak recommendation is made when there is more uncertainty present.Things to consider while rating strength of recommendation: a) Quality of evidence b) Uncertainty about the balance between desirable and undesirable effects c) Uncertainty or variability in values and preferences d) Uncertainty about whether the intervention represents a wise use of resources

APPENDIX A Approaches to identify final search strategy
* As of January 2020, our validation article set included 34 articles available in Medline.As the testing process continued, we added additional articles to the validation set. *

Table 1 .
Approaches to identify final search strategy.The table presents information from testing on January 10, 2020.The same searches rerun today would retrieve additional records.** As of January 2020, our validation article set included 34 articles available in Medline.As the testing process continued, we added additional articles to the validation set. *